1. Field of the Invention
This invention belongs to a technical field of a communication-type navigation apparatus, and more particularly to a pre-install processing of map data executed at the time of initial setting of the navigation apparatus.
2. Description of Related Art
A known navigation apparatus utilizes map data stored in a map data storage medium such as a CD-ROM (Compact Disc-Read Only Memory) or a DVD-ROM (DVD-Read Only Memory). Namely, the navigation apparatus includes a drive unit for the map data storage medium such as a CD-ROM or a DVD-ROM, and reads out map data around the current position of the vehicle according to the movement of the vehicle to display the map data on a LCD (Liquid Crystal Display) or the like attached on the vehicle near a driving seat of the vehicle.
However, in the case of using such a storage medium as a data supply source of map data, there is a problem that frequently updating the map data is difficult. The map data is updated in accordance with the expansion road network. Also, the map data used by the navigation apparatus includes, in addition to road data, information such as neighboring facilities and/or shops (e.g., road-side shops, gas stations and soon). Recently, shops open and shut up relatively frequently. A user who always needs new information should frequently buys and changes the map data storage medium, and this is burdensome for the user. In addition, a new edition of map data storage medium is put into the market every certain time period, e.g., every 6 months or every year, and hence the user cannot catch up with the on-going real change of the shops or stores even if he or she buys a new edition every time.
Moreover, recently functions of the navigation apparatus are being improved and sophisticated, and the map data includes more auxiliary data, other than the road data. Hence, the navigation apparatus needs to employ a microprocessor having high-speed processing capability to enable sophisticated route search and/or route guidance. This increases the size and the cost of the navigation apparatus.
In order to overcome the above-mentioned problems, recently a communication-type navigation system has been proposed. In such a communication-type navigation system, a navigation apparatus installed on a vehicle and a map data providing center on a communication network communicate with each other by wireless communication, and map data is downloaded from the map data providing center to the navigation apparatus on the vehicle. The navigation apparatus stores the downloaded map data on an internal storage medium such as a hard disk, and performs map display and/or route guidance by using the stored map data. Examples of such a communication-type navigation apparatus are disclosed in Japanese Patent Applications Laid-Open under No. 7-262495 and No. 10-96644.
In such a communication-type navigation system, by updating the map database on the map data providing center side, a user can always obtain and use newest map data by communication with the map data providing center.
However, connecting the map data providing center to download map data requires communication cost that is charged to the user. Therefore, the user should pay a large amount of communication fee if he or she downloads all of the necessary map data by the communication with the map data providing center.